Abstract

As climate change drives sea levels higher, coastal habitats may adapt by migrating inland. This landward shift may be challenged, however, by the presence of human-made and natural barriers, which may result in coastal habitat loss and declines in associated fish and wildlife populations. This is commonly known as ‘coastal squeeze’. To support the resilience of Northwest coastal habitats as sea levels rise, scientists and resource managers require a greater understanding of the risks posed by coastal squeeze as well as potential management responses and policy options for addressing those risks.

The Northwest Climate Adaptation Science Center’s (NW CASC) 2023 Deep Dive convened natural resource managers and scientists from across the Northwest in a virtual working group process to review what is known and unknown about managing coastal squeeze in the Northwest.

This review yielded the following key findings:

• While the drivers of coastal squeeze are being observed in the Northwest (i.e., sea level rise, anthropogenic and natural barriers), relatively few studies have explicitly measured its impacts (i.e., declines in coastal species and habitats).
• A broad array of potential adaptation strategies for addressing coastal squeeze has been identified in the literature. However, evaluation of their effectiveness has been conducted primarily at a national or global scale, challenging local application to the Northwest.
• A variety of tools are available to assist managers in understanding the driving factors and components of coastal squeeze. However, few, if any, tools comprehensively address all components or are easily accessible for application to decision-making.
• Many Northwest resource managers are observing and preparing for sea-level rise but their ability to address coastal squeeze is limited by development pressure, private property interests and local politics.
• Many Northwest resource managers believe that removing built infrastructure will help address coastal squeeze, but lack knowledge about how to address coastal squeeze when built infrastructure remains.
• Resource managers on the Northwest coast use a range of technical resources to inform their decision-making, but need complementary information about local conditions, social considerations and case studies to inform actions related to coastal squeeze.
• A limited number of policies and government entities address coastal squeeze, but do so only indirectly (e.g., via sea level rise adaptation planning). The degree to which policy considers landward habitat migration within other related climate adaptation planning is not fully understood.
• Opportunities for policy and regulation to alleviate coastal squeeze exist at the federal, state and local levels, but vary depending on site-specific conditions, jurisdictional authority, political will and funding availability, among other factors.
• Coastal squeeze may impact the natural and cultural resources coastal habitats provide to Northwest communities. These impacts may fall disproportionately on historically marginalized communities. Co-developing coastal squeeze responses with local communities and Tribes can help ensure just, equitable and culturally grounded adaptation decisions.

The Deep Dive process also identified research and capacity-building needs for effective management of coastal squeeze in the Northwest. Research needs include more comprehensive analysis of the drivers of coastal squeeze and anticipated impacts on coastal species and habitats, identifying potential adaptation and management actions, analyzing potential policy approaches for addressing coastal squeeze, understanding tribal actions and adaptation barriers, and a greater understanding of public preferences and attitudes toward management options. Capacity-building needs include improved assessment and decision-support tools, development of knowledge-sharing networks, funding for proactive management actions, increased staff capacity across stakeholder groups and agencies, and public outreach and communication regarding coastal squeeze impacts and adaptation actions.

Results and products of the 2023 Deep Dive will help inform actionable science investments by the NW CASC and its partners to support management of coastal squeeze in the Northwest. In addition, the co-production of 2023 Deep Dive results and products by scientists and managers helped build a Northwest community of practice around this emerging climate risk through peer-to-peer learning, networking and a cross-disciplinary exchange of knowledge and ideas.

Affiliated Organizations

Northwest Climate Adaptation Science Center (NW CASC)

Established in 2010, the Northwest CASC (NW CASC) provides regionally-relevant scientific information, tools, and techniques to resource managers and communities in Washington, Oregon, and Idaho. Its purpose is to provide scientific information, tools, and techniques that managers and other parties interested in land, water, wildlife and cultural resources can use to anticipate, monitor, and adapt to climate change.

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Climate Impacts Group (CIG)

The Climate Impacts Group (CIG) is an internationally recognized interdisciplinary research group studying the impacts of natural climate variability and global climate change (“global warming”). Research at the CIG considers climate impacts at spatial scales ranging from local communities to the entire western U.S. region, with most work focused on the Pacific Northwest (PNW). Through research and interaction with stakeholders, the CIG works to increase community and ecosystem resilience to fluctuations in climate.

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